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1

Enhancement of reliability of process power plant by connecting SVC in generator bus during grid fault

Goswami U., Sadhu P. K., Chakraborty S.

Journal of Power Technologies

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2018

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Vol. 98, nr 3

239--244

EN

Fault clearing time plays an important role in maintaining power system stability and process survivability during major system faults under a variety of system configuration and topologies. Grid disturbance in the power system presents a very distinct challenge; lack of a utility interconnection hinders the system’s ability to recover from loss of generation. The key factor in plant survivability during a grid fault is optimal use of a fast acting governor and a Flexible Alternating Current Transmission System device (FACTS) to maintain power system stability. In this paper, the core objective is to increase the critical fault clearing time of captive generator sets during a grid fault without violating the transient stability criteria recommended in IEC standards. As a remedial measure, a static VAR Compensator (SVC) was connected to the generator bus. For simulation purposes an IEEE General Steam-Turbine (STM) governor model and an IEEE AC5A excitation model were considered. During a grid fault the transient performance of captive generator sets was observed with and without connecting SVC in generator bus.

2

Development of a hybrid meta-model for material selection using design of experiments and EDAS method

Chatterjee P., Banerjee A., Mondal S., Boral S., Chakraborty S.

Engineering Transactions

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2018

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Vol. 66, iss. 2

187--207

EN

Selection of materials for a specific application is one of the extremely demanding problems in a synchronised manufacturing environment as it directly determines perceptible quality and cost of the product. Material selection is a complex process, intending to choose the best material while satisfying a pre-decided set of requirements. Material selection decision is made during preliminary product design stage. An improperly chosen material leads not only to an early component failure but also to a redundant cost involvement. There are numerous materials and various criteria influencing the material selection process for a particular application. Although a good amount of multi-criteria decision-making (MCDM) methods are available to deal with this type of selection applications, this paper aims to propose a hybrid method of design of experiments (DOE) and evaluation based on distance from average solution (EDAS) to solve material selection problems in current industrial applications. DOE and EDAS are used jointly to determine the critical material selection criteria and their interactions by fitting a polynomial to the experimental data in a multiple linear regression analysis. A gear material selection problem is demonstrated to establish the application competence of the DOE-EDAS method. Application results were validated with the results of the previous researchers and they indicate that the proposed DOE-EDAS hybrid model is straightforward, robust and practical in solving complex MCDM problems.

3

Eigen value approach to generalized thermoelastic interactions in an unbounded body with circular cylindrical cavity without energy dissipation

Chakraborty S.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 4

811--825

EN

The theory of generalized thermoelasticity in the context of the Green-Naghdi model -II (thermoelasticity without energy dissipation) is studied for an infinite circular cylindrical cavity subjected to two different cases of thermoelastic interactions when the radial stress is zero for (a) maintaining constant temperature and (b) temperature is varying exponentially with time. The Laplace transform from time variable is used to the governing equations to formulate a vector matrix differential equation which is then solved by the eigen value approach. Numerical computations for the displacement component, temperature distribution and components of thermal stress have been made and presented graphically.

4

Barriers in the Advancement of Solar Energy in Developing Countries like India

Chakraborty S., Sadhu P. K., Goswami U.

Problemy Ekorozwoju

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2016

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Vol. 11, nr 2

75--80

EN

The present paper puts an emphasis on the current energy market scenario and different types of barriers associated with the advancement of solar energy in a developing countries like India. Solar energy, best suited for urban environment, can be housed in a limited space and is characterized as a pollution free, environmentally friendly, as well as noise-free source of electricity. Among the available renewable energies, solar energy is considered to be an integral one, owing to its reduction in cost at an exponential rate day-by-day. The present study deals with the potential of solar energy market in the Indian subcontinent along with several other problems that it needs to overcome in order to be established as an independent system.

PL

Artykuł omawia scenariusze związane ze współczesnym rynkiem energetycznym, wskazując na różnorodne typy barier, na które napotyka rozwój energii solarnej w krajach rozwijających się, takich jak Indie. Energia słoneczna doskonale sprawdza się w warunkach miejskich, przeznaczone do jej pozyskiwania instalacje nie potrzebują dużo miejsca i nie zanieczyszczają powietrza, a ponadto nie emitują hałasu. Wśród różnorodnych źródeł energii to właśnie energia solarna wydaje się być najbardziej korzystna, biorąc pod uwagę jej nieustannie malejące koszty. Niniejsza praca przedstawia potencjał rozwoju rynku energii słonecznej w Indiach, zwracając szczególna uwagę na problemy, które należy rozwiązać, aby mógł on funkcjonować, jako niezależny system.

5

Damage detection of bridge girder pier system from modal data

Roy S., Chakraborty S., Sarkar S. K.

International Journal of Applied Mechanics and Engineering

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2005

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Vol. 10, no 4

679-688

EN

The equation error based system identification method is found to be efficient for identifying the element properties directly without iterations. But its application is limited to truss type structures only. The equation of error approach of identification algorithm is extended here for a frame element to asses the existing damage of the bridge girder-pier system from simulated modal data. The problem is formulated as an optimization program where the error norm of the Eigen equation is minimized. A Monte Carlo based error sensitivity analysis is performed to investigate the behavior of the algorithm. Finally, the formulation is elucidated through a three span continuous bridge girder model simply supported on piers.

6

On nonlinear waves in elastic conductors under a magnetic field

Chakraborty S.

Archives of Mechanics

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2002

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Vol. 54, nr 1

3-13

EN

A study of the behavior of magneto-elastic waves in a nonlinear isotropic elastic conductor by applying the method of multiple scales and perturbation has been made for a general displacement wave, under the action of an arbitrarily directed, uniform magnetic field. While in the case of transverse magnetic field the shock the waves are formed, it has been shown here that, under an oblique magnetic field, the wave is distorted without the formation of shocks.

7

Stochastic finite element method for sensitivity analysis of structures

Bhattacharyya B., Chakraborty S.

Applied Mechanics and Engineering

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2000

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Vol. 5, no 4

867-882

EN

The conventional sensitivity analysis of structures is based on the assumption of complete certainty of design parameters. However, occurrence of uncertainty is unavoidable in structures. In the present work, an attempt has been made to study the response sensitivity, considering the effect of uncertainty in structural design parameters. The random parameters are modeled as Gaussian stochastic process and simulated through covariance matrix decomposition. The advantages of Neumann expansion technique has been utilized in deriving the finite element solution of the response sensitivity within the framework of Monte Carlo simulation. Numerical examples are presented to explain the accuracy and efficacy of Neumann expansion method over direct simulation the process.

8

An efficient stochastic finite element method for random field problems

Chakraborty S., Sekhar Dey S.

Applied Mechanics and Engineering

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1999

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Vol. 4, no 1

45-71

EN

The present paper primarily deals with the analysis of structures involving more than one parameter being stochastic in nature. The proposed method involves two stages. The first part hinges upon adequate representation of the stochastic process and a digital simulation of random parameters. This has been achieved by the local averaging technique followed by the Cholesky decomposition algorithm. Finally, the finite element solution has been obtained utilizing the Neumann expansion method within the framework of Monte Carlo simulation.The approach involves only single decomposition of the stiffnes matrix for the entire simulation and leads to a considerable saving of computing time. Another important flexibility of the approach is that more than one parameter can be handled simultaneously. Numerical examples are presented to elucidate the accuracy and efficiency of the method with respect to the direct simulation approach.

9

On distortion of waves in a nonlinear magnetoelastic conductor

Chakraborty S.

Archives of Mechanics

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1998

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Vol. 50, nr 6

1048-1053

EN

Wave distortion and formation of shocks due to the elastic nonlinearity of the medium in the presence of a magnetic field are studied using the multiple scalec technique for a one-dimensional travelling longitudinal wave. Condition for formation of shocks has been obtained for a sinusoidal signal.

10

Seismic transmission tomography a configurative approach

Chakraborty S., Nath S., Sengupta S.

Acta Geophysica Polonica

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1998

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Vol. 46, nr 4

389-408

EN

Seismic Transmission Tomography provides a method for direct estimation of velocity distribution in the subsurface from the P- or S-wave first arrival traveltime data. Both the data acquisition configuration and the reconstruction algorithm are equally important in imaging the subsurface lithostratigraphic unit. Out of the three transmission tomographic configurationssurface-to borehole, borehole-to-surface and cross-hole, the latter is ussually used in the transmission tomographic fiels investigation. The present study has two aims: (i) to test the performance of the SimultaneousInterative Reconstruction Technique (SIRT) algorithm coded here, and (ii) to show the necessity of a combined interpretation of the three source-reciver configurations. Using the standard formulations, initial parametrization is possible but not exact solution in terms of the velocity distribution in the subsurface and the location of an anomalous body in the halfspace. The SIRT scheme is found to yield satisfactory estimates of the subsurface from the data acquired by the three configurations. Both the synthetic and actual shear wave seismic tomographic data for the detection of galleries at North Searsole Colliery, Raniganj Coalfields, West Bengal, India, are used for an extensive analysis. The resoults presented in the form of raster images undoubtedly show the effectiviteness of SIRT scheme and also the good resolution acheved by a combined interpretation of the surface-ti-borehole, borehole-to-surface and cross hole omographic data.